Method for tuning an oscillating receiver circuit of a transponder built into a RFID system

US6272321A · kind A · utility

Assignee

• TEMIC Semiconductor GmbH · DE

Inventors

• Michael Bruhnke · Munich, DE
• Konrad Hirsch · Blaustein, DE
• Marc Melchior · Hohenkammer, DE
• Andreas Schulgen · Unterschleißheim, DE

Key dates

• Filing date: Jul 12, 1999
• Grant date: Aug 7, 2001
• Expiry date: Jul 12, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G11C11/419
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

The invention relates to a method for calibrating an oscillating receiver circuit of a transponder in an RFID system to resonance to the frequency of an inquiry signal transmitted by a reader, the oscillating receiver circuit comprising at least one inductive resistor and at least one capacitor. Immediately after the start of reception of the inquiry signal, capacitors are connected in increments to the capacitance of the oscillating receiver circuit until such time as the rectified, smoothed inquiry signal assumes a maximum voltage value. This active self-calibration is performed upon each initialization of the transponder but can also be addressed by having the reader send a special sequence to the transponder.